I'm not sure, but I believe it uses the name the DN used to register with the 
NN.  But…  The NN will reject registrations from unresolvable hostnames so I 
believe DNS is mandatory.

Daryn

On Mar 11, 2013, at 12:58 PM, Steven Matthews wrote:

> I'm writing some test code to try out the WebHDFS REST API for potentially 
> adding functionality to a program. If I want to create and write to a file 
> using the API, I would send the initial create request and I would get back a 
> location of a datanode as the documentation says I should. The location I'm 
> getting back however is a name and not an IP. Now if had this name registered 
> in my DNS server or put in an entry in my hosts file then I can successfully 
> make the 2nd create call using that name and I would have just created a 
> file.  Is there any reason why it doesn't respond with an IP address? Is this 
> something that it could be configured to do? In a fully-distributed Hadoop 
> setup this would seem like a big pain to register and maintain all the 
> datanode names and their IPs for machines across the internet just so I can 
> resolve a name.
> 
> -Steven

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